Dell E172fpb

[longnempty]

Re: Dell E172fpb

Hi Doc,

Is the monitor still working? Ive been watching this forum with great interest. I also own an E172fpb, just over one year old, and it died. Same symptoms. Thanks,

Mike

[dockarl]

Re: Dell E172fpb

Yep - still working ok. One of the other (old) trannies I didn't replace went out in sympathy, causing the same old 'on for two seconds then off' (interestingly usually corrected for about 20 mins or so by unplugging the monitor, leaving off for 10 secs or so then plugging in and turning on again) so i ended up replacing the other two trans as well about a week ago - so far so good. Will update if anything else happens.

Could be worth considering whether or not to do away with the transistor control alltogether and just run the backlights at full herbs? I'll think about how to do this if the necessity arises.

All the best,

Doc

[dockarl]

Re: Dell E172fpb

longempty, it's interesting that yours failed at just over one year old too - mine also - just out of warranty - now call me a cynic, but perhaps there is a 'bastard warranty expiry detector chip' somewhere in these things, along the same lines as the 'need to use urgently' detector chip built into consumer equipment such as photocopiers, the 'driver in a hurry' detector chip in traffic lights on the route to work, and the 'user has forgotten his battery charger' chip built into mobile phones to ensure the battery discharges at twice the normal rate when away from home.. just a thought

Doc

[dockarl]

Re: Dell E172fpb

I must add - the transistors in question get BLOODY HOT - hotter than I would have thought would be usual, even given the large number of watts they are designed to handle. I've thought about adding a small fan etc - but that really begs the question - WHY ON EARTH should you need to go to these lengths to keep it cool? I reckon Benq has simply done a pretty shoddy job when it comes to design and reliability testing on this model, and I hope they've ironed the problems out now for their newer models.

Doc

[longnempty]

Re: Dell E172fpb

Hi again Doc,

I just received some new MJE3055, havent put them in yet. Strange that they get so hot? Wonder if the back lights are pulling too much power, ie, shorting out? I agree with these monitors going bad so soon. Might have been made that way on purpose. Good Luck Doc, later,

Mike

[sjbso2000]

Re: Dell E172fpb

I had the same problem. Power light flashing on and off. I replaced the four trannies (as documented by Dockarl) and now have the same problem as Prototech where the screen comes on for 2 sec's and then goes off with the green light still on (not flashing now).

Any info on the transformers / availability, etc.....?

[dockarl]

Re: Dell E172fpb

Hi STJB!

Before you go buying another transformer it might be worthwhile making ABSOLUTELY CERTAIN that you installed the new transistors the same way as the old ones - and check the data sheets to DOUBLE CHECK that the E C and B for your transistor are aligned with those printed on the board.

Also, could be worth checking for continuity between the legs on the new transistors and their relative tracks, just in case you have a solder joint problem.

Mine still going strong ladies and gentlemen (at this stage)..

All the best,

Doc

[sjbso2000]

Re: Dell E172fpb

Dockarl, you're a legend............ that's only if I can get my monitor to work following your advice!!

I kept my eye on the leg alignment more than anything else. No need to worry there.

I will strip it back down and check continuity.

NOTE: Before reading the rest of this I must tell you all now, (as well as being half p!ssed) my background to electonics is VERY VERY basic. In fact the last time I was tought how to use a soldering iron was back in when I was 13 in secondary school (15 years ago!). I'm now a fully qualified Technical engineer, but still haven't picked up a soldering iron since then (only those big fcukers they give you during your apprenticeship to make you look stupid to manually heat over an oven to solder cups and tin metal and sh!t)

The funny thing is, I sent my monitor off to a family friend (he runs his own tv repair business) who replaced one transistor and ran it for two days in his office to make sure. It worked fine. I had it back and after 2 hours it failed again.

He then replaced 'the pair' of trannies and ran it for a week.... then it failed again. He said it was the transformer that was faulty and he couldn't get spares. Fair enough. I got my monitor AND my money back.

Reading Dockarl's post made me think. I'd already read it and printed it out to give the 'family' repair guy a head start.

I decided to see if following Dockarl's advice I could make things better myself.

I went to Maplins to get the components specified in Dockarl's post. Hey Presto, after guiding them through THEIR OWN catalogue they had the ones I wanted (about 0.80GBP each).

I took the E172fpb to pieces and noticed the four trannies that caused so much grief (q7whatever) were TINY in comparison to the replacements (a VERY small body and a very small metal back which I guess could be a heat sink?). The family friend obviously replaced them with the original components (or very very very similar).

This gave me more confidence in what Dockarl said, bigger replacements, more space (cut away the metal bits on the monitor body!)... and hopefully be able to absorb more heat. I think that's logical. Makes sense to me. A lot less heat absorbed, so, less chance of failing.

So, all trannies replaced. Switch on. The splash screen appears (no pc connected). Then, after 2 secs, no picture. Only green power button on constant.

Weird thing is, I can switch it off via the power button, and then switch it back on and the screen re-appears again for a couple of seconds, and then goes off again.

Surely this isn't one of the transformers going bad. If it was, would the components have burnt(?) and I'd have the same 'flashing' problem as I had orignally?

Something for you boffins to solve.

P.S. One thing I did notice before I gave it a go myself, the only time my montior failed was when it was in sleep (yellow button) mode and i tried to awaken it my moving the mouse. When it was awoken it was flashing green mode!!!!!

Good luck,

SJBSO2000

[jumba]

Re: Dell E172fpb

Since replacing the second set of transitors with 2SD1804 and turning off the power to the screen when in standby, I had no problems. After sketching out the circuit it appears that there are 2 transformers for each side that are identical only one that's driven by the tranistors. For some reason the tranistors blow and then cook the transformers whilst in standby.As I had caught the second pair faily early the board was not discoloured when compared to to the other cct that had been left on for days in standby mode . So if you can get your hands on another dead unit one has the possiblity to 2 to 3 spare transforms to repair another units. Its obvious why the supplier of replacement boards offers $10 for the faulty one and free shipping!

[Drexal]

Re: Dell E172fpb

Hey Guys,

Okay. I didn't have a chance to order new transformers. I ordered the MJE's and installed them. Monitor green light came on for a while, but no picture. Shut it off and turned it back on... poof... flashing green. I was talking with some people and they are pretty sure that inspite of the transformer appearing to be okay it may be shorted to where too much voltage is coming through causing the voltage punch through. So... If I have a chance to order the transformers I'll let u know how things turn out. It's just that I'm too lazy to actually contact the one company to get the transformers. Too bad we still don't know a replacement part number.

Drexal

[jumba]

Re: Dell E172fpb

Hi,
With my Dell, the green light flashing was in unison the back light flashing. The monitor image could be momentarily seen. Does your's do that? Why not remove the faulty tranistors and run the monitor on one back light to see if the unit is basically functioning. My experience with throw away items is, parts are no longer available after manufacturing has ceased. So, short of rebuilding the transformer the chances of getting a replacement is slim, in particular, as these units come from China!

[dockarl]

Re: Dell E172fpb

Hmm..

You are all suceeding in scaring me that my repairs may be temporary, which would be a great shame as one of the fantastic things about this monitor is you can whip out the stand screws, turn it 90 degrees, rip of the metal tap on the display stand and (albeit using only the top two screws to mount it) use it in portrait format instead of landscape (if you have a graphics card that allows that). At the moment I have one widescreen running on my vid card digital output (for viewing webpages etc) and the 'repaired' one running in portrait mode - it is PERFECT for using things like Microsoft word as it fits an entire letter or A4 format page almost perfectly.

Anyway everyone, happy travels, and, STBSO, don't worry about being Pi**ed - friday night is a good time for it, and trying to learn how to solder after 15 years calls for a bit of help

All the best,

Doc

[dockarl]

Re: Dell E172fpb

It would be fantastic if someone could find a copy of the workshop manual for these little buggers - what we could achieve with a decent circuit diagram would be beyond belief.

[jumba]

Re: Dell E172fpb

There is no road map for the dell on the web.

[longnempty]

Re: Dell E172fpb

Hi DocKarl,

Call me a chicken. I got to looking around Dell's website, and the monitor is still under warranty (3 years). I know, buk buk buk. I contacted a Dell rep, via chat, and a new monitor is on the way. You can cuss me if you want. I have the new MJE3055s, but I wont be putting them in. Sorry everybody. Thank you Doc,

Mike

[longnempty]

Re: Dell E172fpb

oops, forgot, the new monitor has NO warranty

[mousie]

Re: Dell E172fpb

Hi folks

As a matter of interest, I came back to have a peek at this site and a few more friends have joined to get their monitors working. Folks, I've had a chance to check out a second board and again a successful repair geting the old tip41c (don't flame me as I had a few lying around) and I must remind people that if you have a DVM on the large diode (see page three) and you see 10v and accelerating quickly up to 14 then you must follow the earlier advice and remove, check and even change the few filtering caps in as stated earlier in thread which was correct advice from the boardsellers If continues to runway in volts then the runaway is linked to dirty contacts on the board, second board repaired with again doing a 3/4 de solder and redo, takes about 10-15mn and presto, second board now has 10.1v steady and first. My problem is I cannot locate area affected but again the second board was a dirty build as was the first. So folks, it will cost you next to nothing but you must do this first and any electronics technition will tell you this prior to exploring more advanced issues like trannies etc. There is nothing special about the NPN's so anything close will do. On the first, my son has racked up well over a couple of hundred hours but I cheated and have the 4 trannies external with heatsinks tucked under the mid section between rgb and power. The heat coming from inside minus these trannies is still pretty high compared to the acer's etc. Remember, board first (because of all the effort getting out, caps next followed by diode and trannies. Remember caps do change value with age and heat thats why these are first off the board for checking. Good luck, with the work folks

[Raith]

Re: Dell E172fpb

I too have had the 'pleasure' of my E172FPb fail on me with the common blinking green led. I also discovered that Q759 and Q760 had shorted and hence went about replacing these transistors. I opted for a couple of BD911's and replaced the duff components, however when put back together the same symptoms were present. I today figured out that the tips of the new componets were touching the metal casing - in essence causing a short. A few strips of tape accross the back of casing and all is well.

[enkay78]

Re: Dell E172fpb

folks,
have been busy with work and couldn't take time off to look at my monitor. well comin to the point i managed to force supply the IC751 by passing the Q761 and my ccfl backlights started to glow(i think this is the "full herbs" scenario that dockarl was talking about). But once i connect my AD board and my control panel pins dont work plus the led glows at a solid greenish yellow and i dont get to see the monitor self test on the display. looked like the ad/logic board got cooked. this is gonna be a lot more trickier than the inverter fix. anyone has any tips to fix the same?? does anyone have norris part's customer support email id which works??

thanks n regards
enkay78
ps: i have ordered a new samsung 931b as a replacement but i am very keen on using this dell monitor as a guniea pig to hone my repairing skills.

[technicalwiz]

Re: Dell E172fpb

Hi Guys the 2sc5707 is avalible for B&D electronics fro the states however if the can get a 2sc5706 this will do just as well, these fail due to bad soldering around the inverter, only other fault i have on these is the opto coupler goes funny, never had any bad caps on these at all. cheers